Anti-counterfeiting, latent fingerprint detection and optical thermometry using a multi-stimulus down-converting La2CaZnO5:Er3+ phosphor

Abstract

The development of new inorganic phosphors for the use of latent fingerprint detection and anticounterfeiting applications has aroused attention. In this report, a series of Er (0.5–4 mol %) doped La2CaZnO5:Er3+ phosphors are prepared by a simple solution combustion process. The photoluminescence emission (PLE) intensity is found to be dependent on the Er3+ ions concentration and its maximum value is achieved when the doping concentration is 1 mol %. From theoretical analysis, one knows that the concentration quenching mechanism is dominated by the electric dipole-dipole interaction with a critical distance of 14.84 Å. The temperature sensing capabilities of the resulting compounds are investigated on the basis of the temperature-dependent PLE from the 2H11/2 and 4S3/2. The sensor sensitivity of the examined samples increased up to 11.45% K−1 at 300 K. The sensor sensitivity of the obtained phosphor affected hardly varied by the doping concentration. The optimized phosphor powder is utilized for LFP and anticounterfeiting applications. The results clearly found that powder dusting method exhibited high contrast, high sensitivity, high selectivity, and extensive applicability in fingerprint development. We have established a straightforward dip pen, screen printing, and inkjet printing techniques for designing various patterns from the fabricated anti-counterfeiting security ink.